Sep 21, 2011 12:37 PM

We have been discussing the potential of BSF larvae for use in composting in the UK. They have recently become available commercially in the UK as a food in the exotic pet industry (calciworms), some enthusiasts are breeding their own BSF in artificial environments.

We had concerns regarding negligent release, although we think the UK does not have sufficient sunlight hours for adults to breed, we have not reached a conclusion as to possible knock on effects to native species. The public literature shows wide European distribution, from Portugal, Croatia, Albania through to Turkey, but we can't find any reliable sightings in the UK.

I wonder if anyone knows of a similar British species that could be utilised in a similar manor?

A suitable species would lay eggs on or near decomposing vegetable matter, spend most of it's life cycle in the larval stage, and show no potential to become a pest.

There are some good advantages to using BSF larvae in composting, the larvae are voracious, deter house flies, and the adults have no mouth parts. The larvae can be utilised as poultry or fish food, they do not taint the flavour of eggs as the house fly maggot does, they are also a very good source of calcium and protein.

First of all, I have seen no papers describing Hermetia as being an indigenous or even an established species in the UK. It is more then likely that it has been imported in its larval stages in organic products on many occasions but how often that resulted in emerging adults I do not know.

I have no way to confirm whether conditions in the UK are suitable for breeding or not. The Asian ladybird was not suppose to be able to breed here, I think, and it now is all over the place.

The UK list has a number of species that can be found near rotting vegetation and occasionally even seem to prefer compost heaps. The species I have most often seen associated with compost heaps is Sargus bipunctatus, a relatively large species (smaller than Hermetia, though), less often the other species of Sargus. Chloromyia formosa and Microchrysa polita I have myself reared from larvae and pupae collected from under grass heaps. These species are smaller than Sargus species but may well be suitable for your puppose if the material to be composted is mainly composed of grass.

You are correct, as the origin of Hermetia is the Americas, however, they have established themselves world wide with the advent of trade routes. I see no reason why they wouldn't have established themselves in the capital of the colonial world and yet be present in Holland, Belgium, and north of France.

Like the lady bird, I can imagine that they have adopted themselves also.

Overall the black soldier fly is a low priority species when it comes to academic papers. Prior to the last 10 years and the research of Dr Craig Sheppard, there were only 2 academic papers on the species. Even, those were sponsored by a pesticide company and only exploring potential ways of killing them.

A potential great academic resource would be a locally experienced forensic entomlogyst. They can often observe the species when assesing the time of death.

Can you please quote me the sources for the Netherlands and Belgium?. I am from the Netherlands myself and I am unaware of it being established here (let alone even being recorded formally). The latest review dealing with species that might prove to be a risk (see the pdf downoadabble from http://www.pensoft.net/journals/biorisk/article/618/abstract/) lists about the same countries for Hermetia illucens as Fauna Europaea (which may be outdated). I cannot rule out that with the gradual rise in temperature the time might be near we will find them in the Low Countries.

The only paper on distribution I have found was T Üstüner et al 2003 (ISSN: 14334968) though I have no academic access to the full paper, the abstract reads: “Known data on the distribution of Hermetia illucens (L.) in Europe are summarized and updated. This species has been reliably recorded from Portugal, Spain, France, Switzerland, Italy, Malta, Croatia and Albania. A new record from Turkey represents the easternmost finding in the West Palaearctic and a new species to the fauna of the whole of the Near East. It may be evidence of a recent extension of this species in the Mediterranean area.”

Switzerland being two hardiness zones colder than the UK it seems likely BSF could survive in the UK.

Further, I have two reports from amateur spotters in the UK, one unconfirmed sighting in Sussex who has seen adults from March to October. Another confirmed sighting from Worcestershire (who can send me photos if required) in June this year.

Novartis (A UK biomedical/larvicide supplier) have a "UK residents only" webpage which states "The black soldier fly may become extremely abundant in poultry manure (especially in high-rise or deep pit houses), and in swine manure pits; in these types of animal housing it may become the major fly species." Since this is a UK only page, taken with the known sightings, it hints at BSF breeding naturally in the UK.

I have been unable to find reference to any negative environmental impacts from this species. Although Novatis say it is a target pest species for their larvicides, the only effect for farmers is in how the larvae tend to liquefy manures, (making it easier for poultry to contaminate eggs for e.g.) which would be better handled by educating the farmers in better/specific manure management techniques as to how they can utilise BSFL as a sellable resource, as it is in many countries already, rather than selling them chemicals.

There is the possibility BSF could push native niche species out of their habitat, however the climatic restrictions here are probably more suited to native species so I think this a low probability. I have read some parasitic wasps prefer BSFL as hosts than other species in some countries, which may indeed help native species of parasitic wasp.

I am planning a field trip to some organic poultry and pig farms in the South next year, I would prefer to harvest BSF in the wild as they are probably more acclimatised than either imported, or BSFL bred in the UK in artificial environments, though I will also utilise UK bred larvae in a composting unit as they are likely to attract wild specimens by their presence.

I would not necessarily accept a description of the species on a 'UK residents only' page as a sign of proof that it should be a British species. I can recall having seen a mentioning of an adult (or more?) in the UK but I would be interested to see pictures. As to the record of adults from March to October, well I would say not impossible but why has that never been picked up by the dipterists community in the UK? Anyway, if they were there from March till October it must have been last year (or perhaps earlier) and since they were spotted over a longer period it must have been a resident. Please, let him (her?) collect some specimens so we can confirm ID. The temperature not being too bad should mean they are still about.

Just a side step: On my website Diptera.info there have been at least about 30 ID queries for this species. From these queries I can add Slovenia and Greece to the list of european countries. One British larva was queried but that was discounted by a specialist with experience in the forensic field.

Agreed the Novartis site is not proof Paul, merely a hint as I said. I do think it unlikely they would use it in the UK sales pitch if there were no BSFL issues here. I suspect Novartis are unlikely to help in confirmation as supplying help to people trying to utilise the BSFL in composting is likely to impact their sales of larvaicide, if it were up to me we would irradiate the larvacide via education, rather than the BSFL!

The unconfirmed sightings from March to October in Sussex was a post on a forum from 2008.

I have spent over 50hrs trawling the web this week for further information/sightings regarding UK prevalence, I have sent out over 40 email requests for information, evidence is very limited! I will update this thread if I come across any relevant information.

Thanks for the link and info Robert, I will be joining your forum soon, it looks like an excellent resource. I have spent some time there, but I wanted to confirm BSF is in the UK already before I take the plunge into BSFL composting.

I sell BioPod™ Plus Black Soldier Fly grub composters. We have sold a few units to Britain without significant feedback (people call when they can't get it started). Had a customer near Brugge, Belgium that did have issues attracting the species for months and eventually he found some at a local pig farm.

Also, I heard there was a group in Holland cultivating BSF for a project to decompose pig manure. I believe that this was a private enterprise venture and not a university project. I heard that project also had a lot of difficulty and the yields of grubs was very low. I suspect that this is because the deep pit systems utilized in the study have very old manure and not nutrient rich fresh manure. Overall i think you can find the species when you look/try hard enough. But... for the species to become nich dominant (like they are in other climates) local adaptation is required.

I was not aware of any success in Switzerland and assume this must be some lower altitude areas.